Several prior art land, water, and amphibious vehicles have had suspension systems or undercarriages associated therewith. For example, Johnson U.S. Pat. No. 2,339,782 discloses a sectional boat utilizing wheels which are removable but not retractable. Henningsen U.S. Pat. NO. 2,460,935 describes a boat-trailer combination utilizing a lever mechanism which lifts the wheels when the boat structure is folded open. This system relies on telescoping members for absorbing shocks and can only be used in the fully retracted or fully down positions. Bushfield U.S. Pat. No. 2,588,084 includes a retractable suspension system for a combined trailer-folding boat. This system is of the folding type and apparently does not include any shock absorbing means. Howe U.S. Pat. No. 3,042,942 discloses an amphibious pontoon boat including a retractable suspension system. The shock absorbing system associated therewith utilizes a tension spring. Sideways folding of the wheels does not permit use of the system for supporting the boat at varying levels. Byberg U.S. Pat. No. 3,079,616 discloses a foldable floating platform utilizing a vertical-lift type rack and pinion mechanism for retracting the wheels. No shock absorbing system is included. Stockmann U.S. Pat. No. 3,114,157 discloses a raft including a rather complex supporting mechanism, which mechanism includes numerous parts subject to undue lateral forces. Mycroft U.S. Pat. No. 3,280,785 accomplishes lifting of the wheels by compressing Volkswagen suspension springs thereby pulling the wheels with a cable-tensioning mechanism. Finally, Lusk U.S. Pat. No. 3,738,684 discloses a transportable vehicle including a removable or foldable telescoping undercarriage, which undercarriage can support the vehicle at only one fixed position.
From the above, it is apparent that the prior art suspension systems or undercarriages generally provide at most one or two of the many features which are desirable in a land, water, or amphibious vehicle suspension system. Most of these prior art systems include numerous parts and sliding surfaces subject to wear thereby requiring extensive corrosion protection. Therefore, it is desirable and advantageous to have a unitary suspension system providing all the desired features for land, water, or amphibious applications.
Objects of the present invention are therefore to provide:
a unitary suspension system;
a compact suspension system;
a retractable suspension system;
a retractable suspension system which is readily adaptable for land travel, and stationary and water applications;
a retractable suspension system which is utilizable in camping and boating type vehicles;
an adjustably retractable suspension system;
an adjustably retractable suspension system comprising a minimum number of parts and which is of simple design and economical to manufacture;
a unitary suspension system or undercarriage which is readily adaptable for land, water, or amphibious vehicles;
a suspension system of the above type whose associated wheel need not be removed for water use;
a suspension system of the above type whose associated wheel is fully retractable;
a suspension system of the above type whose associated wheel is adjustably retractable;
a suspension system of the above type including shock absorbing means;
a suspension system of the above type including shock absorbing means of the compressed spring type;
a suspension system of the above type including a jack screw assembly for effecting partial or full retraction of the associated wheel;
a suspension system of the above type including stiff jack screw means for effecting retraction of the associated wheel;
a suspension system of the above type including a minimum number of parts and sliding surfaces; and
a suspension system of the above type which is readily adaptable for raising or lowering the associated vehicle.